Reactions of steroidal epoxides with strong organic bases and an investigation into the syntheses of some labelled pregnane derivatives

dc.contributor.author

Jahangir.

en_US

dc.date.accessioned

2009-10-02T13:20:16Z

dc.date.available

2009-10-02T13:20:16Z

dc.date.issued

1982-10-02T13:20:16Z

dc.identifier.uri

http://hdl.handle.net/10464/2761

dc.description.abstract

Reactions of 5,6- and 4,5-epoxycholestane derivatives with strong
bases were investigated.
Epoxidation of 3a-acetoxycholest-5-ene also gave a new compound along
with the anticipated epoxides. Interconversions of the latter were observed.
Some possible mechanisms of its formation and rearrangements have been
pIioposed.
No reaction was observed with any of the 5,6- and 4,5-steroidal
epoxides employed in the present study, using potassium tertiary butoxide
under refluxing conditions. n-Butyllithium reacted only with
5,6-epoxycholestanes bearing a ketal moiety at the C3 carbon. Opening of
the ketal group was observed with n-butyllithium in the case of a ~-epoxide.
The reaction was also investigated in the absence of epoxide functionality.
A possible mechanism for the opening of ketal group has been proposed.
Lithium diethylamide (LDEA) was found effective in rearranging
5,6- and 4,5-epoxides to their ~orresponding allylic alcohols. These
rearrangements presumably proceed via syn-eliminations, however the
possibility of a corresponding anti-elimination has not been eliminated.
A substituent effect of various functional groups (R = H, OH, OCH2CH20)
at C3 has-been observed on product distribution in the LDEApromoted
rearrangements of the corresponding epoxides.
No reaction of these epoxides was observed with lithium diisopropylamide
(LDA) •
In the second part of the project, several attempts were made towards
the sYRthesis of deoxycorticoste~one~17,2l,2l~d3' a compound desirable for
the 2l-dehydroxylation studies of deoxycorticosterone. Several routes were
investigated, and some deuterium labelled pregnane derivatives were
prepared in this regard. Microbial 21-hydroxylation of progesteronel7,21,21,2l-
d4 by ~ niger led to loss of deuterium from C21 of the product.
An effort was made to hydroxylate progesterone microbially under neutral
condtions.

en_US

dc.language.iso

eng

en_US

dc.publisher

Brock University

en_US

dc.subject

Epoxy compounds.

en_US

dc.subject

Steroids.

en_US

dc.subject

Organic bases.

en_US

dc.subject

Pregnane.

en_US

dc.subject

Organic compounds--Synthesis.

en_US

dc.title

Reactions of steroidal epoxides with strong organic bases and an investigation into the syntheses of some labelled pregnane derivatives